Re: [PATCH v15 01/17] uaccess: add untagged_addr definition for other arches

[Khalid Aziz]

On Mon, 2019-05-06 at 18:30 +0200, Andrey Konovalov wrote:
> To allow arm64 syscalls to accept tagged pointers from userspace, we
> must
> untag them when they are passed to the kernel. Since untagging is
> done in
> generic parts of the kernel, the untagged_addr macro needs to be
> defined
> for all architectures.
> 
> Define it as a noop for architectures other than arm64.
> 
> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> ---
>  include/linux/mm.h | 4 ++++
>  1 file changed, 4 insertions(+)

As discussed in the other thread Chris started, there is a generic need
to untag addresses in kernel and this patch gets us ready for that.

Reviewed-by: Khalid Aziz <khalid.aziz@xxxxxxxxxx>

> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 6b10c21630f5..44041df804a6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
>  #include <asm/pgtable.h>
>  #include <asm/processor.h>
>  
> +#ifndef untagged_addr
> +#define untagged_addr(addr) (addr)
> +#endif
> +
>  #ifndef __pa_symbol
>  #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
>  #endif